This invention relates to a traction type transmission having a high speed change ratio, and more particularly to a traction type transmission capable of transmitting smoothly power of ultra-high speed revolution as high as tens of thousands of revolutions per minute at a high speed change ratio.
Recent transmissions for gas turbines or blowers are required to be able to change the speed of power of ultra-high speed revolution as high as 30,000-45,000 r.p.m. It is known, however, that various difficulties are encountered when such an ultra-high speed revolution is changed by transmission gears. This is because lubrication of a tooth surface cannot be made sufficiently and the occurrence of a machining error of the gears is unavoidable, and the machining error increases vibration with an increasing speed of revolution and consequently, transmission of the ultra-high speed revolution becomes extremely dangerous.
In order to prevent defects of such ultra-high speed revolution, various counter-measures such as correction of the gear profile after machining, the use of a very expensive bearing for ultra-high speed revolution, improved lubrication methods and the like are necessary in addition to mere precision machining of the gears. However, the apparatus will become extremely expensive if all of these requirements are satisfied.